1 /* 1 /*
2 * Key Wrapping: RFC3394 / NIST SP800-38F 2 * Key Wrapping: RFC3394 / NIST SP800-38F
3 * 3 *
4 * Copyright (C) 2015, Stephan Mueller <smuell 4 * Copyright (C) 2015, Stephan Mueller <smueller@chronox.de>
5 * 5 *
6 * Redistribution and use in source and binary 6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that t 7 * modification, are permitted provided that the following conditions
8 * are met: 8 * are met:
9 * 1. Redistributions of source code must reta 9 * 1. Redistributions of source code must retain the above copyright
10 * notice, and the entire permission notice 10 * notice, and the entire permission notice in its entirety,
11 * including the disclaimer of warranties. 11 * including the disclaimer of warranties.
12 * 2. Redistributions in binary form must repr 12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the 13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials pro 14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used t 15 * 3. The name of the author may not be used to endorse or promote
16 * products derived from this software with 16 * products derived from this software without specific prior
17 * written permission. 17 * written permission.
18 * 18 *
19 * ALTERNATIVELY, this product may be distribu 19 * ALTERNATIVELY, this product may be distributed under the terms of
20 * the GNU General Public License, in which ca 20 * the GNU General Public License, in which case the provisions of the GPL2
21 * are required INSTEAD OF the above restricti 21 * are required INSTEAD OF the above restrictions. (This clause is
22 * necessary due to a potential bad interactio 22 * necessary due to a potential bad interaction between the GPL and
23 * the restrictions contained in a BSD-style c 23 * the restrictions contained in a BSD-style copyright.)
24 * 24 *
25 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY 25 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
26 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 26 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS FOR A PARTIC 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
28 * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT S 28 * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
29 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL 29 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT L 30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
31 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF US 31 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
32 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND O 32 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
33 * LIABILITY, WHETHER IN CONTRACT, STRICT LIAB 33 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
35 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED O 35 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
36 * DAMAGE. 36 * DAMAGE.
37 */ 37 */
38 38
39 /* 39 /*
40 * Note for using key wrapping: 40 * Note for using key wrapping:
41 * 41 *
42 * * The result of the encryption operati 42 * * The result of the encryption operation is the ciphertext starting
43 * with the 2nd semiblock. The first se 43 * with the 2nd semiblock. The first semiblock is provided as the IV.
44 * The IV used to start the encryption 44 * The IV used to start the encryption operation is the default IV.
45 * 45 *
46 * * The input for the decryption is the 46 * * The input for the decryption is the first semiblock handed in as an
47 * IV. The ciphertext is the data start 47 * IV. The ciphertext is the data starting with the 2nd semiblock. The
48 * return code of the decryption operat 48 * return code of the decryption operation will be EBADMSG in case an
49 * integrity error occurs. 49 * integrity error occurs.
50 * 50 *
51 * To obtain the full result of an encryption 51 * To obtain the full result of an encryption as expected by SP800-38F, the
52 * caller must allocate a buffer of plaintext 52 * caller must allocate a buffer of plaintext + 8 bytes:
53 * 53 *
54 * unsigned int datalen = ptlen + crypto_ 54 * unsigned int datalen = ptlen + crypto_skcipher_ivsize(tfm);
55 * u8 data[datalen]; 55 * u8 data[datalen];
56 * u8 *iv = data; 56 * u8 *iv = data;
57 * u8 *pt = data + crypto_skcipher_ivsize 57 * u8 *pt = data + crypto_skcipher_ivsize(tfm);
58 * <ensure that pt contains the p 58 * <ensure that pt contains the plaintext of size ptlen>
59 * sg_init_one(&sg, pt, ptlen); 59 * sg_init_one(&sg, pt, ptlen);
60 * skcipher_request_set_crypt(req, &sg, & 60 * skcipher_request_set_crypt(req, &sg, &sg, ptlen, iv);
61 * 61 *
62 * ==> After encryption, data now contain 62 * ==> After encryption, data now contains full KW result as per SP800-38F.
63 * 63 *
64 * In case of decryption, ciphertext now alrea 64 * In case of decryption, ciphertext now already has the expected length
65 * and must be segmented appropriately: 65 * and must be segmented appropriately:
66 * 66 *
67 * unsigned int datalen = CTLEN; 67 * unsigned int datalen = CTLEN;
68 * u8 data[datalen]; 68 * u8 data[datalen];
69 * <ensure that data contains ful 69 * <ensure that data contains full ciphertext>
70 * u8 *iv = data; 70 * u8 *iv = data;
71 * u8 *ct = data + crypto_skcipher_ivsize 71 * u8 *ct = data + crypto_skcipher_ivsize(tfm);
72 * unsigned int ctlen = datalen - crypto_ 72 * unsigned int ctlen = datalen - crypto_skcipher_ivsize(tfm);
73 * sg_init_one(&sg, ct, ctlen); 73 * sg_init_one(&sg, ct, ctlen);
74 * skcipher_request_set_crypt(req, &sg, & 74 * skcipher_request_set_crypt(req, &sg, &sg, ctlen, iv);
75 * 75 *
76 * ==> After decryption (which hopefully 76 * ==> After decryption (which hopefully does not return EBADMSG), the ct
77 * pointer now points to the plaintext of 77 * pointer now points to the plaintext of size ctlen.
78 * 78 *
79 * Note 2: KWP is not implemented as this woul 79 * Note 2: KWP is not implemented as this would defy in-place operation.
80 * If somebody wants to wrap non-align 80 * If somebody wants to wrap non-aligned data, he should simply pad
81 * the input with zeros to fill it up 81 * the input with zeros to fill it up to the 8 byte boundary.
82 */ 82 */
83 83
84 #include <linux/module.h> 84 #include <linux/module.h>
85 #include <linux/crypto.h> 85 #include <linux/crypto.h>
86 #include <linux/scatterlist.h> 86 #include <linux/scatterlist.h>
87 #include <crypto/scatterwalk.h> 87 #include <crypto/scatterwalk.h>
88 #include <crypto/internal/cipher.h> <<
89 #include <crypto/internal/skcipher.h> 88 #include <crypto/internal/skcipher.h>
90 89
91 struct crypto_kw_block { 90 struct crypto_kw_block {
92 #define SEMIBSIZE 8 91 #define SEMIBSIZE 8
93 __be64 A; 92 __be64 A;
94 __be64 R; 93 __be64 R;
95 }; 94 };
96 95
97 /* 96 /*
98 * Fast forward the SGL to the "end" length mi 97 * Fast forward the SGL to the "end" length minus SEMIBSIZE.
99 * The start in the SGL defined by the fast-fo 98 * The start in the SGL defined by the fast-forward is returned with
100 * the walk variable 99 * the walk variable
101 */ 100 */
102 static void crypto_kw_scatterlist_ff(struct sc 101 static void crypto_kw_scatterlist_ff(struct scatter_walk *walk,
103 struct sc 102 struct scatterlist *sg,
104 unsigned 103 unsigned int end)
105 { 104 {
106 unsigned int skip = 0; 105 unsigned int skip = 0;
107 106
108 /* The caller should only operate on f 107 /* The caller should only operate on full SEMIBLOCKs. */
109 BUG_ON(end < SEMIBSIZE); 108 BUG_ON(end < SEMIBSIZE);
110 109
111 skip = end - SEMIBSIZE; 110 skip = end - SEMIBSIZE;
112 while (sg) { 111 while (sg) {
113 if (sg->length > skip) { 112 if (sg->length > skip) {
114 scatterwalk_start(walk 113 scatterwalk_start(walk, sg);
115 scatterwalk_advance(wa 114 scatterwalk_advance(walk, skip);
116 break; 115 break;
117 } !! 116 } else
>> 117 skip -= sg->length;
118 118
119 skip -= sg->length; <<
120 sg = sg_next(sg); 119 sg = sg_next(sg);
121 } 120 }
122 } 121 }
123 122
124 static int crypto_kw_decrypt(struct skcipher_r 123 static int crypto_kw_decrypt(struct skcipher_request *req)
125 { 124 {
126 struct crypto_skcipher *tfm = crypto_s 125 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
127 struct crypto_cipher *cipher = skciphe 126 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
128 struct crypto_kw_block block; 127 struct crypto_kw_block block;
129 struct scatterlist *src, *dst; 128 struct scatterlist *src, *dst;
130 u64 t = 6 * ((req->cryptlen) >> 3); 129 u64 t = 6 * ((req->cryptlen) >> 3);
131 unsigned int i; 130 unsigned int i;
132 int ret = 0; 131 int ret = 0;
133 132
134 /* 133 /*
135 * Require at least 2 semiblocks (note 134 * Require at least 2 semiblocks (note, the 3rd semiblock that is
136 * required by SP800-38F is the IV. 135 * required by SP800-38F is the IV.
137 */ 136 */
138 if (req->cryptlen < (2 * SEMIBSIZE) || 137 if (req->cryptlen < (2 * SEMIBSIZE) || req->cryptlen % SEMIBSIZE)
139 return -EINVAL; 138 return -EINVAL;
140 139
141 /* Place the IV into block A */ 140 /* Place the IV into block A */
142 memcpy(&block.A, req->iv, SEMIBSIZE); 141 memcpy(&block.A, req->iv, SEMIBSIZE);
143 142
144 /* 143 /*
145 * src scatterlist is read-only. dst s 144 * src scatterlist is read-only. dst scatterlist is r/w. During the
146 * first loop, src points to req->src 145 * first loop, src points to req->src and dst to req->dst. For any
147 * subsequent round, the code operates 146 * subsequent round, the code operates on req->dst only.
148 */ 147 */
149 src = req->src; 148 src = req->src;
150 dst = req->dst; 149 dst = req->dst;
151 150
152 for (i = 0; i < 6; i++) { 151 for (i = 0; i < 6; i++) {
153 struct scatter_walk src_walk, 152 struct scatter_walk src_walk, dst_walk;
154 unsigned int nbytes = req->cry 153 unsigned int nbytes = req->cryptlen;
155 154
156 while (nbytes) { 155 while (nbytes) {
157 /* move pointer by nby 156 /* move pointer by nbytes in the SGL */
158 crypto_kw_scatterlist_ 157 crypto_kw_scatterlist_ff(&src_walk, src, nbytes);
159 /* get the source bloc 158 /* get the source block */
160 scatterwalk_copychunks 159 scatterwalk_copychunks(&block.R, &src_walk, SEMIBSIZE,
161 160 false);
162 161
163 /* perform KW operatio 162 /* perform KW operation: modify IV with counter */
164 block.A ^= cpu_to_be64 163 block.A ^= cpu_to_be64(t);
165 t--; 164 t--;
166 /* perform KW operatio 165 /* perform KW operation: decrypt block */
167 crypto_cipher_decrypt_ 166 crypto_cipher_decrypt_one(cipher, (u8 *)&block,
168 167 (u8 *)&block);
169 168
170 /* move pointer by nby 169 /* move pointer by nbytes in the SGL */
171 crypto_kw_scatterlist_ 170 crypto_kw_scatterlist_ff(&dst_walk, dst, nbytes);
172 /* Copy block->R into 171 /* Copy block->R into place */
173 scatterwalk_copychunks 172 scatterwalk_copychunks(&block.R, &dst_walk, SEMIBSIZE,
174 173 true);
175 174
176 nbytes -= SEMIBSIZE; 175 nbytes -= SEMIBSIZE;
177 } 176 }
178 177
179 /* we now start to operate on 178 /* we now start to operate on the dst SGL only */
180 src = req->dst; 179 src = req->dst;
181 dst = req->dst; 180 dst = req->dst;
182 } 181 }
183 182
184 /* Perform authentication check */ 183 /* Perform authentication check */
185 if (block.A != cpu_to_be64(0xa6a6a6a6a 184 if (block.A != cpu_to_be64(0xa6a6a6a6a6a6a6a6ULL))
186 ret = -EBADMSG; 185 ret = -EBADMSG;
187 186
188 memzero_explicit(&block, sizeof(struct 187 memzero_explicit(&block, sizeof(struct crypto_kw_block));
189 188
190 return ret; 189 return ret;
191 } 190 }
192 191
193 static int crypto_kw_encrypt(struct skcipher_r 192 static int crypto_kw_encrypt(struct skcipher_request *req)
194 { 193 {
195 struct crypto_skcipher *tfm = crypto_s 194 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
196 struct crypto_cipher *cipher = skciphe 195 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
197 struct crypto_kw_block block; 196 struct crypto_kw_block block;
198 struct scatterlist *src, *dst; 197 struct scatterlist *src, *dst;
199 u64 t = 1; 198 u64 t = 1;
200 unsigned int i; 199 unsigned int i;
201 200
202 /* 201 /*
203 * Require at least 2 semiblocks (note 202 * Require at least 2 semiblocks (note, the 3rd semiblock that is
204 * required by SP800-38F is the IV tha 203 * required by SP800-38F is the IV that occupies the first semiblock.
205 * This means that the dst memory must 204 * This means that the dst memory must be one semiblock larger than src.
206 * Also ensure that the given data is 205 * Also ensure that the given data is aligned to semiblock.
207 */ 206 */
208 if (req->cryptlen < (2 * SEMIBSIZE) || 207 if (req->cryptlen < (2 * SEMIBSIZE) || req->cryptlen % SEMIBSIZE)
209 return -EINVAL; 208 return -EINVAL;
210 209
211 /* 210 /*
212 * Place the predefined IV into block 211 * Place the predefined IV into block A -- for encrypt, the caller
213 * does not need to provide an IV, but 212 * does not need to provide an IV, but he needs to fetch the final IV.
214 */ 213 */
215 block.A = cpu_to_be64(0xa6a6a6a6a6a6a6 214 block.A = cpu_to_be64(0xa6a6a6a6a6a6a6a6ULL);
216 215
217 /* 216 /*
218 * src scatterlist is read-only. dst s 217 * src scatterlist is read-only. dst scatterlist is r/w. During the
219 * first loop, src points to req->src 218 * first loop, src points to req->src and dst to req->dst. For any
220 * subsequent round, the code operates 219 * subsequent round, the code operates on req->dst only.
221 */ 220 */
222 src = req->src; 221 src = req->src;
223 dst = req->dst; 222 dst = req->dst;
224 223
225 for (i = 0; i < 6; i++) { 224 for (i = 0; i < 6; i++) {
226 struct scatter_walk src_walk, 225 struct scatter_walk src_walk, dst_walk;
227 unsigned int nbytes = req->cry 226 unsigned int nbytes = req->cryptlen;
228 227
229 scatterwalk_start(&src_walk, s 228 scatterwalk_start(&src_walk, src);
230 scatterwalk_start(&dst_walk, d 229 scatterwalk_start(&dst_walk, dst);
231 230
232 while (nbytes) { 231 while (nbytes) {
233 /* get the source bloc 232 /* get the source block */
234 scatterwalk_copychunks 233 scatterwalk_copychunks(&block.R, &src_walk, SEMIBSIZE,
235 234 false);
236 235
237 /* perform KW operatio 236 /* perform KW operation: encrypt block */
238 crypto_cipher_encrypt_ 237 crypto_cipher_encrypt_one(cipher, (u8 *)&block,
239 238 (u8 *)&block);
240 /* perform KW operatio 239 /* perform KW operation: modify IV with counter */
241 block.A ^= cpu_to_be64 240 block.A ^= cpu_to_be64(t);
242 t++; 241 t++;
243 242
244 /* Copy block->R into 243 /* Copy block->R into place */
245 scatterwalk_copychunks 244 scatterwalk_copychunks(&block.R, &dst_walk, SEMIBSIZE,
246 245 true);
247 246
248 nbytes -= SEMIBSIZE; 247 nbytes -= SEMIBSIZE;
249 } 248 }
250 249
251 /* we now start to operate on 250 /* we now start to operate on the dst SGL only */
252 src = req->dst; 251 src = req->dst;
253 dst = req->dst; 252 dst = req->dst;
254 } 253 }
255 254
256 /* establish the IV for the caller to 255 /* establish the IV for the caller to pick up */
257 memcpy(req->iv, &block.A, SEMIBSIZE); 256 memcpy(req->iv, &block.A, SEMIBSIZE);
258 257
259 memzero_explicit(&block, sizeof(struct 258 memzero_explicit(&block, sizeof(struct crypto_kw_block));
260 259
261 return 0; 260 return 0;
262 } 261 }
263 262
264 static int crypto_kw_create(struct crypto_temp 263 static int crypto_kw_create(struct crypto_template *tmpl, struct rtattr **tb)
265 { 264 {
266 struct skcipher_instance *inst; 265 struct skcipher_instance *inst;
267 struct crypto_alg *alg; 266 struct crypto_alg *alg;
268 int err; 267 int err;
269 268
270 inst = skcipher_alloc_instance_simple( !! 269 inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
271 if (IS_ERR(inst)) 270 if (IS_ERR(inst))
272 return PTR_ERR(inst); 271 return PTR_ERR(inst);
273 272
274 alg = skcipher_ialg_simple(inst); <<
275 <<
276 err = -EINVAL; 273 err = -EINVAL;
277 /* Section 5.1 requirement for KW */ 274 /* Section 5.1 requirement for KW */
278 if (alg->cra_blocksize != sizeof(struc 275 if (alg->cra_blocksize != sizeof(struct crypto_kw_block))
279 goto out_free_inst; 276 goto out_free_inst;
280 277
281 inst->alg.base.cra_blocksize = SEMIBSI 278 inst->alg.base.cra_blocksize = SEMIBSIZE;
282 inst->alg.base.cra_alignmask = 0; 279 inst->alg.base.cra_alignmask = 0;
283 inst->alg.ivsize = SEMIBSIZE; 280 inst->alg.ivsize = SEMIBSIZE;
284 281
285 inst->alg.encrypt = crypto_kw_encrypt; 282 inst->alg.encrypt = crypto_kw_encrypt;
286 inst->alg.decrypt = crypto_kw_decrypt; 283 inst->alg.decrypt = crypto_kw_decrypt;
287 284
288 err = skcipher_register_instance(tmpl, 285 err = skcipher_register_instance(tmpl, inst);
289 if (err) { !! 286 if (err)
290 out_free_inst: !! 287 goto out_free_inst;
291 inst->free(inst); !! 288 goto out_put_alg;
292 } <<
293 289
>> 290 out_free_inst:
>> 291 inst->free(inst);
>> 292 out_put_alg:
>> 293 crypto_mod_put(alg);
294 return err; 294 return err;
295 } 295 }
296 296
297 static struct crypto_template crypto_kw_tmpl = 297 static struct crypto_template crypto_kw_tmpl = {
298 .name = "kw", 298 .name = "kw",
299 .create = crypto_kw_create, 299 .create = crypto_kw_create,
300 .module = THIS_MODULE, 300 .module = THIS_MODULE,
301 }; 301 };
302 302
303 static int __init crypto_kw_init(void) 303 static int __init crypto_kw_init(void)
304 { 304 {
305 return crypto_register_template(&crypt 305 return crypto_register_template(&crypto_kw_tmpl);
306 } 306 }
307 307
308 static void __exit crypto_kw_exit(void) 308 static void __exit crypto_kw_exit(void)
309 { 309 {
310 crypto_unregister_template(&crypto_kw_ 310 crypto_unregister_template(&crypto_kw_tmpl);
311 } 311 }
312 312
313 subsys_initcall(crypto_kw_init); 313 subsys_initcall(crypto_kw_init);
314 module_exit(crypto_kw_exit); 314 module_exit(crypto_kw_exit);
315 315
316 MODULE_LICENSE("Dual BSD/GPL"); 316 MODULE_LICENSE("Dual BSD/GPL");
317 MODULE_AUTHOR("Stephan Mueller <smueller@chron 317 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
318 MODULE_DESCRIPTION("Key Wrapping (RFC3394 / NI 318 MODULE_DESCRIPTION("Key Wrapping (RFC3394 / NIST SP800-38F)");
319 MODULE_ALIAS_CRYPTO("kw"); 319 MODULE_ALIAS_CRYPTO("kw");
320 MODULE_IMPORT_NS(CRYPTO_INTERNAL); <<
321 320
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